Crystal structure of 3,6-diphenylpyrrolo[3,4-c]pyrrole-l,4-dione–3,6-bis(4-tert-butylphenyl)-2,5-dihydropyrrolo[3,4-c]pyrrole-l,4-dione (1:1), ( C18H12N2O2 ) · ( C26H28N2O2 )

Abstract

droxide, followed by protonation with hydrochloric acid [1]. MX-DPP was then purified by sublimation at about 610 K, using two-zone furnace [2]. Organic pigments are quite insoluble in organic solvents. Thus, after a long optimization of the growth parameters, it is possible to grow single crystals from the vapor phase in a closed system. Red platelet crystals of the title compound were obtained after 48 hours. Experimental detailsThe present crystal is extremely small and the crystallinity is rather poor. Therefore, only isotropic refinement has been carried out on MX-DPP. Nevertheless, the bond parameters seem to be quite reasonable. Refinement was done using 769 reflections with 7 0 bs > 1 o(Iobs)· However, the threshold expression of 7 0 bs > 2 a(Iobs) was used for calculating Rgt(F) (409 reflections). No additional peaks were found on difference Fourier maps. DiscussionThe 1:1 mixed crystal (MX-DPP) contains two kinds of diketopyrrolopyrroles known as industrially important red pigments: diketo-diphenylpyrrolopyrrole (DPP) [3,4] and dikctobis(ferf-butylphenyl)pyrrolopyrrole (BTB-DPP) [5]. We have recently found that MX-DPP composed of DPP and BTB-DPP gives practically the same electronic spectra as well as the X-ray diffraction diagrams as those of the hybrid compound of DPP and BTB-DPP; diketo-mono(rerf-butylphenyl) pyrrolopyrrole (MTB-DPP) [1,6]. The present coincidence of these physical properties is of great scientific interest and also of industrial interest, because the color specified by expensive MTB-DPP (due to the synthesis of asymmetrical molecules) can be achieved by inexpensive DPP and BTB-DPP (due to the synthesis of symmetrical molecules). Previously, we have reported the crystal structure of MTB-DPP [7], This shows that there is a NH-0 hydrogen bond network and the molecules are arranged in a fashion "bricks in a brick wall". In addition, the r-butyl group of MTB-DPP faces the phenyl ring of the neighboring one.